comp hardware

• Advantages of networks:

  • Computers can share resources such as printers
  • Files can be accessed through any computer in the network
  • Data can be backed up centrally on a network server
  • Users can logon to any computer and access their work
• Disadvantages of networks:

  • Purchasing the network hardware is expensive
  • Managing a large network is complicated
  • Viruses may be able to infiltrate the network and infect every computer
  • If the server breaks, no-one can connect
• In a star network, all of the computers and other devices (known as nodes) connect to a central switch.  
• Advantages of a star network


  • Fast data transfer – the switch directs data traffic to each device very efficiently
  • If one network cable fails the other computers are not affected
• Disadvantages of a star network:


  • Requires additional hardware such as the central switch and network cables
  • If the central switch fails the whole network goes down
• Mesh networking:


  • All devices connect to other devices either wired or wirelessly
  • Nodes act as routers for data in order to transfer data around the network
  • A partial mesh network is usually used, often in conjunction with star topologies to create larger networks
  • Can be very expensive, also some nodes may not be used and so are redundant
• Wireless Mesh Networks

  Only one node needs a wired Internet connection – no other cabling or infrastructure is required

  • The more nodes that use the network, the more routes there are for data to travel through
  • A node within broadcast distance of three other nodes, will have triple the standard bandwidth
  • As the distance between one node and another is halved, signal strength becomes four times stronger
• Router 


  • Routers connect one or more networks together
  • Looks at the destination of packets of data and sends them to the network that is closest towards their destination
  • A home router will route packets between the home LAN and the Internet
• Switch 


  • Switches connect each node (computer) in a network
  • They know the MAC address of all connected computers and devices
  • When a packet of data arrives, they can send it directly to the correct computer
• NIC – Network Interface Card/Controller
• A NIC allows a device to connect to a switch using either ethernet cable or using wifi, in the case of a wireless NIC

  Every NIC has a unique number called a MAC address which identifies it
• The switch communicates with the NIC to transfer data from one device to another
• Wireless access point (WAP)


  • Allows wireless devices to connect to a wired LAN without need for wires
  • Can be built into a home router
• Router

  • Uses IP addresses to forward data packets between networks
  • Usually has a switch and a modem built into it
• Modem


  • Connects to landline telephone line
  • Converts analogue signals to digital signals and vice versa
  • Allows digital signals (binary) to be transferred down telephone line as sound
  • Usually built into router
• The server stores all the software and data files centrally.  It is the most important computer on the network.
• Peer-to-peer networking:

  • Suitable for small networks/companies with few computers
  • No central server (saves money - servers are expensive)
  • All computers store files locally
  • Users must be responsible for own backups and security
  • Can easily see files on all other computers
  • All computers can communicate with each other without going through a server
• A Media Access Control (MAC) address is assigned to each Network Interface Card (NIC) during manufacture
• TCP (Transmission Control Protocol)


  • Breaks up messages sent over the Internet into small chunkscalled “packets”
  • Reassembles the packets at the other end
  • Detects errors
  • Resends lost messages
• • Application layer
  • Transport layer
  • Internet layer
  • Link layer
• Application layer


  Software such as email clients and web browsers create data to send in this layer
• Transport layer


  • The Transport layer organises the data into packets ready to send/receive
  • Uses TCP
• Internet layer


  • The Internet layer is responsible for routing packets
  • Routers operate on this layer
  • Source and destination IP addresses arewritten on to the packets ready for transmission
• Link layer


  • Protocols that control how devices connect either physically or wirelessly operate at this layer